How true, Briggs and Stratton one lungers.
Jim

 

No offense, it was just that I was always intending to put on new heads, cam, intake and carb on, but didn't really know if that would effect the compression or not. I didn't want to invest that money into it and find-out that if I would have done this or that it would have made it better. You know what I mean. I wish I really did know more about this stuff, so I can do it right the first time.

 

The compression ratio which the higher it is equals more horsepower. Very basically, you get more compression from three areas. Type of piston, cam duration and detonation chamber size in the heads. The smaller the more compression.
I think if I was you, I would pull that vintage engine and store it. Then buy a 302 crate that will give you about 300 hp. and enjoy driving that sucker. You will also have to beef up other parts of the car to handle that horsepower, but that is the fun in owning one of these guys. They are meant to be driven.
Now, if you were my age, I would suggest you put that D code back to stock specs and not race it.

 

Here we go again, spending someone elses money. Let's see, a 64 'D' code 289 is a - 5 bolt to the bell housing engine. A 'crate' 302 motor is a - 6 bolt to the bell housing engine. Simply said, there is more here than meets the eye -
Jim

 

He's asking for opinons Jim, not asking how to conserve money and fix the car the cheapest way. Yeah, I love spending other people's money. Like I said, if it was mine, I would put that D code engine back into original condition, then venture on to other restoration projects. He is obviously a kid who wants more umph than that D code can give him. The alternative is to slap a crate in there, then later on in life put the D code back in.

 

It's not a one for one swap. There's more here than meets the eye -
Jim

 

Really how much HP will changing a 9.01:1 to a 10.01:1 make, about 20HP. I don't think I would really miss that 20 horsepower if I keep the 9.01:1 and add the intake, cam, carb and some heads. I did some quick math and putting in a crate would be over 2 grand more. I am not racing my Mustang or even have a desire to, but I would like some more umph.

If I do add the heads, etc. and keep all my original parts, I could still go back to stock at anytime without much trouble, unless I crack the block. I don't know what to do.

What spurred this on is that my Motorcraft needs to be rebuilt, and is really doggy when I give it some gas from a stand still. I think I will just start with the intake and carb, and see if that satisfies my urges for now. If not I will have to think about what I really want out of my Mustang.

 

There's compression, then there's compression...heh. Like Soaring said, camshaft....static compression is the typical CR people talk about, 9.0:1 or 10:1 in this case, but that really doesn't mean a whole lot, what matters far FAR more is the dynamic or actual compression(the actual compression begins when the intake valve closes AFTER the piston has already started to move up). That, as Soaring said, is effected by the camshaft(more specifically, the timing of the valve events for the cam). If your engine is 9:1 static CR and let's say, 8:1 dynamic, and you change to 10:1 static, but it's still 8:1 dynamic(that would come from a cam that causes the intake valve to close later) then you actually don't have ANY more compression. Let's say you rebuild an engine at 9:1 static like it is now, but go up to 8.5:1 dynamic, you haven't changed the compression ratio, but have actually increased the compression. Then, you have to deal with detonation and fuel availability, it's harder these days to get higher compression because of lower octane fuels that are less tolerant of heat and pressure. Piston dwell angle also affects how combustion occurs which changes the nature of the liklihood for compression and the static and dynamic CR you can run with fuel avilability. So, as you can see, there's a LOT more to it than meets the eye(to coin Norm's phrase), and if you don't understand it you can easily pick the wrong parts and build an engine that runs like crap. If you don't understand it the best thing to do, is either learn, and wait several years(or however long it takes) until you do and can build it yourself, or you can buy a crate engine like the Ford Racing GT-40. Alternatively you could do an h/c/i from a company like Edelbrock that has picked all the parts for you, then have the block rebuilt by a local reputable shop(don't put new heads on an oldcar with a lot of miles, you could end up with problems if you have worn rings) and then just bolt it together if you can turn a wrench. Mist people with limited engine knowledge opt for the h/c/i kit(heads/cam/intake combination btw) and install it themselves with success. But you MUST make sure everything works together, or you may end up building a dog

 

I've never been a fan of slapping performance equipment onto an engine without
1) understanding what your goal is and how it can be achieved
2) rebuilding the short block - if the stock 289 isn't in really good condition even rebuilding the upper end of the engine with stock components can cause issues with blow by and other problems.

My vote for spending solidGas' money would be to change the rear gears, some headers, dual exhaust and performance muffler (so you at least "hear" more umphj) then drive it for a while.

Do a compression check on the engine BEFORE spending any real money.